Cyanogen, C.sub.2 N.sub.2 (CAS 460-19-5), is a highly poisonous, colorless gas which is acrid and pungent in lethal concentrations. Due to its high stability and reactiveness cyanogen has many uses in a wide variety of organic syntheses. For example, cyanogen is employed to prepare diaminoglyoxime and diaminofurazan. The latter two compounds have important and significant uses to modify the exponent and burn rates of solid propellants, such as, for example, those propellants used in gas generators and rocket motors. Additionally, cyanogen has been found useful in the preparation of certain pharmaceutically active compounds as well as useful in the production of carbon fibers.
Heretofore, two general methods for the production of cyanogen have been employed. In the first method, cyanogen is prepared by adding an aqueous solution of sodium or potassium cyanide to an aqueous solution of copper II sulfate or chloride. In the second method, cyanogen is prepared by the vapor phase reaction between hydrogen cyanide and chlorine gas at elevated temperatures.
Problems with the first method include a low yield of cyanogen, i.e. about 41%, and the production of the toxic by-product CuCN. In the second method, the reagents used are very toxic gases, namely HCN and C1.sub.2. The reaction conditions require the toxic gases to be reacted in a quartz reactor in the presence of a carbon catalyst at an average temperature of 650.degree. C. This procedure requires some specialized apparatus. In addition, the cost to maintain a high temperature is quite expensive.
Additionally, it has been proposed to produce cyanogen from HCN and CuO. However, in addition to the use of a highly toxic gas as a reactant and the need for special reaction vessels, the process produced many undesirable by-products. Moreover, prior processes for the production of cyanogen have required careful monitoring of temperature and/or pressure.
It is therefore desirable that an improved process for the production of cyanogen be provided which produces cyanogen in an improved yield and without production of toxic by-products. A further object of this invention is to provide a process for the production of cyanogen which utilizes readily available reagents which are not toxic gases. A still further object of this invention is to provide a process for the production of cyanogen which requires neither specialized process equipment nor elevated pressure. It is yet another object of this invention to provide such a process which utilizes non-toxic solids and liquid reactants and proceeds within a reasonable temperature range. Yet another object of this invention is to provide such a process in which any by-products produced are useful or easily disposed of, or purified or recycled.